FR3027944A1 - GENERATING STRUCTURAL ELEMENTS FOR SUBTERRANEAN FORMATION USING STRATIGRAPHIC IMPLICIT FUNCTION - Google Patents

Abstract

A method, apparatus, and program product may use an implicit stratigraphic function, for example, of the type used in connection with volume-based modeling, to generate structural information for a subterranean formation. In particular, structural information for a subterranean formation can be generated by determining a location in a relevant volume in the subterranean formation from underground formation data associated with the subterranean formation, accessing a numerical model exhibiting a variant implicit stratigraphic function. monotonically defined within the relevant volume to determine a value of the implicit stratigraphic function that corresponds to the determined location, and generating at least one structural element for the subsurface formation from the implicit stratigraphic function of the model numerically based on a spatial distribution of the determined value within the relevant volume.

Description

BACKGROUND [0001] Reservoir modeling and simulation is commonly used in the oil and gas industry to model the structure and / or properties of an underground formation, for example, of the type containing extractable hydrocarbons. Reservoir modeling and simulation may be used during different exploration and production phases, including, for example, an attempt to predict the location, quantity and / or value of extractable hydrocarbons, in order to plan the development. wells to economically extract hydrocarbons from underground formation, and to guide future and / or ongoing production and development decisions. [0002] Reservoir modeling and simulation can be a challenge because data collection techniques such as seismic surveys and well logs can provide an incomplete picture of the structure and other properties of the reservoir. an underground formation, especially when a subterranean formation is severely faulted and / or has another complex structure. Therefore, despite the increasing sophistication of computer modeling techniques, manual interpretation of data collected by specialized personnel in many circumstances is still relied upon to generate structural information that represents the structure of the geological layers that extend. through an underground formation. For example, determining the position of geologic layers within a subterranean formation generally involves manual interpretation of seismic survey data and / or well log data to identify common patterns in the data at different locations. in the subterranean formation that indicate that a given geological layer is distributed through the subterranean formation. In several computer models, the geologic layers are represented by the surfaces between contiguous geological layers, which are generally referred to as horizons. [0003] Well correlation, for example, is a method by which well logs are collected along the lengths of multiple drill holes are analyzed to try to identify where each borehole intersects the same horizon. The intersection of a borehole with a horizon is commonly called a well top, and when wells of the same horizon are found in multiple drill holes, the location and trajectory of a layer A geological model through an underground formation can be better represented in a computer model, for example, by refining the position of the geological layer thus predicted from a seismic survey to correspond to the positions of the wells. However, it has been found that a well correlation can be long and difficult, particularly when a subterranean formation is severely faulted and / or when wells follow complex well paths. In many cases, three-dimensional reservoir grids can be repeatedly reconstructed when additional analysis is performed and additional information is added by a user, resulting in an extended duration of the process of constitution and total refinement of a computer model of underground formation. [0005] Therefore, there is still a need in the art for an improved system for generating structural information for subterranean formation, for example, for the purpose of constituting or refining a computer model of an underground formation. . Summary Embodiments disclosed herein disclose a method, apparatus, and program product that utilizes an implicit stratigraphic function, for example, as used in connection with volume-based modeling, to generate information. structures for underground formation. In particular, embodiments of the invention can generate structural information for a subterranean formation by determining a location in a relevant volume in the subterranean formation from subterranean formation data associated with the subterranean formation. accessing a numerical model having a monotonically defined stratigraphic implicit function defined within the volume concerned to determine a value of the implicit stratigraphic function that corresponds to the determined location, and generating at least one structural element for training from the implicit stratigraphic function of the numerical model on the basis of a spatial distribution of the determined value within the volume concerned. These and other advantages and features which characterize the invention are set forth in the claims appended hereto and form an additional part thereof. However, for a better understanding of the invention, and the advantages and objectives achieved by using it, reference should be made to the drawings as well as the associated description, which describe illustrative embodiments of the invention. This summary is only provided to present a selection of concepts that are described in detail below in the detailed description, and is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid to limit the scope of the claimed object. Brief Description of the Drawings Figure 1 is a block diagram of an exemplary hardware and software environment for a data processing system according to the implementation of various technologies and techniques described herein. Figures 2A to 2D illustrate simplified schematic views of an oilfield having underground formations containing reservoirs according to implementations of different technologies and techniques described herein. Figure 3 illustrates a schematic, partially cross-sectional view of an oilfield having a plurality of data acquisition tools positioned at different locations along the oilfield to collect data from underground formations according to implementations of different technologies and techniques described here. Figure 4 illustrates a production system for performing one or more oil field operation (s) according to implementations of different technologies and techniques described herein. FIG. 5 illustrates components of an example of a volume-based structural modeling framework, including input interpretations of faults and horizons, a tetrahedron grid, and a relative stratigraphic age represented by a periodic color palette. Figure 6 is a flow diagram illustrating an exemplary flow of operations for correlating wells according to an implementation of different technologies and techniques described herein. Figure 7 is a flowchart illustrating another example of a flow of operations for correlating wells according to an implementation of different technologies and techniques described herein. Figure 8 illustrates an example of a well top extraction operation performed on a graphical representation of a first and second well tracks. Figure 9 is a flowchart illustrating an example of a sequence of operations for interactively extracting well vertices according to an implementation of different technologies and techniques described herein. Figure 10 is a flowchart illustrating an example of a sequence of operations for interactively interpreting seismic data according to an implementation of different technologies and techniques described herein. Figure 11 is a flowchart illustrating an example of a sequence of operations for integrating rare data according to an implementation of different technologies and techniques described herein.

Detailed Description [0020] The embodiments described herein disclose a method, an apparatus, and a program product that generate structural information for a subterranean formation based on an implicit stratigraphic function of a structure-based structural framework. the volume of the underground formation.  In particular, in several embodiments of the invention, structural information generally represented by one or more structural element (s) such as wells vertices, horizons , horizon interpretation objects, seismic attributes of geological layers, faults, etc. , can be generated for an underground formation, for example, a geographical region of the Earth.  An underground formation may include, for example, a land or sea reservoir containing extractable hydrocarbons, and for purposes of disclosure, an affected volume may refer to any volume in a geographic region of the Earth.  An implicit stratigraphic function can be considered to be a monotonically varying function that is based on the stratigraphic age in the subterranean formation, and from which a value representative of the stratigraphic age (for example, a Relative geological age or stratigraphic thickness relative to a reference) can be determined on the basis of a three-dimensional position in the subterranean formation, for example, represented by Cartesian or other coordinates (e.g., (x, y, d) , where x and y are geographical coordinates and d is a depth below a reference depth such as surface or sea level).  For example, a value representative of the stratigraphic age may be a scalar attribute such as a relative geologic age attribute (AGR) in several embodiments of the invention.  An implicit stratigraphic function varies monotonically as it increases or decreases monotonically from at least one oldest horizon to the most recent horizon in a given volume.  As will be appreciated by those skilled in the art of the present disclosure, a single value of the stratigraphic implicit function can define a conformal horizon surface across a relevant volume, and because of geological faults and other discontinuities (e.g. angular unconformities resulting from erosion processes or lack of deposition), such a surface can be discontinuous through these geological discontinuities.  Moreover, in several embodiments (for example, where there is no significant fold or fault), within each conformal sequence an implicit stratigraphic function attribute may be proportional to the reported distance, or cumulative distance to a reference surface, or a ratio of a stratigraphic thickness that separates two contiguous surfaces and a stratigraphic thickness to one of the surfaces.  Therefore, in several embodiments, for a given value of the stratigraphic implicit function, a spatial distribution of this value may exist through at least a portion of a relevant volume in a subterranean formation.  A volume-based modeling structural framework (VBM) generally refers to a structural framework that incorporates a numerical model of an underground formation that primarily models volumes (eg, geological layers, fault blocks, geological bodies, etc. ) as opposed to the surfaces surrounding these volumes, which is based at least in part on an implicit stratigraphic function, as described above, such that the distribution of the implicit stratigraphic function is known or can be interpolated everywhere within a relevant volume.  In an example of a VBM structural framework, a structural framework can be constructed by forming a tetrahedron grid constrained by known faults in the subterranean formation, interpolating values of the implicit function on the nodes of the tetrahedron grid (for example, using a linear least squares formulation), and then generating surfaces that represent implicitly modeled horizons based on an iso-surfacing algorithm.  The implicit function can in several embodiments be an implicit stratigraphic function.  In several embodiments consistent with the invention, a graphical representation of underground formation data associated with the subterranean formation is generated and displayed to a user, and a user input directed to that graphical representation is used to specify a selected location relating to the graphical representation.  A graphical representation in this regard is a graphical or visual representation of subterranean formation data such as well logs, two-dimensional or three-dimensional displays of a reservoir or subterranean formation (for example, including visual representations of well paths of one or more existing or proposed wells), seismic traces, seismic images, seismic cubes, interpreted seismic horizons, faults and geological body boundaries (eg salt bag, dike, etc. ), interpreted wells (ie, intersections between well paths and subterranean features), surfaces and maps extracted or interpolated from those interpretations, or other types of data that characterize the structure or other properties of an underground formation.  In these embodiments, the selected location relating to the graphical representation can be used to determine a location in a relevant volume in the subterranean formation, so that a numerical model can be accessed, such as it can be incorporated in a VBM structural framework, to determine a value of an implicit stratigraphic function associated with this numerical model which corresponds to the determined location in the volume concerned.  The determined value can then be used to generate at least one structural element for the subterranean formation, as well as to cause the display of a graphical representation of the at least one structural element in the graphical representation of the subterranean formation data.  For example, in several embodiments, displaying the graphical representation of the at least one structural element may include modifying the graphical representation of the subterranean formation data to include the graphical representation of a structural element or superimpose the graphical representation of a structural element to the graphical representation of underground formation data, among other techniques.  It will be appreciated that in several embodiments, displaying a graphical representation may include generating real graphic data that is displayed locally on a computer screen coupled to a computer, for example , in the case of a stand-alone or single-user computer system.  In other embodiments, for example, in web-based or client-server embodiments, displaying a graphical representation may include generating data and / or instructions that, when they are communicated to a different computer, cause that computer to generate the graphic data that is finally displayed on a computer screen coupled to that different computer.  In other embodiments, the determination of a location in a concerned volume may not be based on a directed user input on a graphical representation, for example, in cases where structural elements are generated in a batch process, structural data can be selected automatically by applying a filter to a combination of attributes such as the data type (well top, seismic interpretation, etc.). ), the absolute or relative stratigraphic age, the geological type (eg erosion, fault, conformal horizon, etc.) ), the name of the geological formation, the data medium (well road, seismic survey), the sub-volume or the area concerned (fault block, geological layer, region or contiguous volume (e) defined ) arbitrarily, surface or plane of arbitrary intersection, etc. ), the value or range of one or more petrophysical (s) or geometric (s) attributes (depth, porosity, etc.) ), or such as the geometric intersection between existing structural elements (for example a well and a surface, a map and a cross-section, etc.). ), etc.  Furthermore, it will be appreciated that in several embodiments, no graphical representation can be generated to generate structural elements, and it may be sufficient that the structural elements are simply generated for use in a subsequent analysis or interpretation of the structure. an underground formation, as an input for the calculation of geometric attributes (eg depth, thickness, etc.) ) or the construction of other structural elements, surfaces, maps, grids, lattices, etc.  Thus, in several embodiments, a location in a relevant volume in a subterranean formation can be determined from subterranean formation data associated with the subterranean formation, a numerical model having an implicit stratigraphic function varying in a monotonic manner defined at within the relevant volume can be accessed to determine a value of the implicit stratigraphic function that corresponds to the determined location, and at least one structural element for the subsurface formation can be generated from the implicit stratigraphic function of the numerical model on the basis of a spatial distribution of the determined value within the volume concerned.  In one illustrative embodiment, the techniques disclosed herein can be used to interactively generate well vertices for a plurality of wells in a subterranean formation.  In such an embodiment, the graphical representation of subterranean formation data may comprise a graphical representation of subterranean formation data for each of a first and a second borehole formed in the subterranean formation. user input may include a user selection of a first wellhead proposed for the first borehole on the graphical representation of subterranean formation data for the first borehole, the location of the inlet of the user may include a depth along the first wellbore that corresponds to the user's selection of the first proposed well top, access to the numerical model to determine the value of the implicit stratigraphic function may include the determination from the value of the implicit stratigraphic function to the depth along the first borehole, the generation of at least one structural member may include generating, for the second borehole, a second proposed well top that corresponds to the first well vertex proposed for the first borehole based on the determined value of the implicit stratigraphic function, and driving the display of said at least one structural element in the graphical representation of the subterranean formation data may include driving the display of a graphical representation of the second proposed well vertex on the graphical representation of underground formation for the second borehole.  In several embodiments, the graphical representations of underground formation data for the first and second boreholes may each comprise a well bore of a well log, whereas in several embodiments, the graphical representations. Underground formation data for the first and second boreholes may each include a well path in a three-dimensional view.  In a plurality of embodiments, the subterranean formation data may include subterranean formation data for each of the first and second boreholes formed in the subterranean formation, the location in the volume concerned may include a depth along the first wellbore which corresponds to a first wellhead proposed for the first borehole, access to the numerical model to determine the value of the implicit stratigraphic function may include determining the value of the implicit stratigraphic function at the depth along the first borehole, and generating at least one structural element may include generating, for the second borehole, a second proposed well top that corresponds to the first well vertex proposed for the first hole drilling on the basis of the determined value of the implicit stratigraphic function.  Additional embodiments may also include sampling the implicit stratigraphic function along each of a first and a second well path, respectively, which correspond to the first and second boreholes, where the access to the numerical model to determine the value of the implicit stratigraphic function may include determining the value from the implicit stratigraphic function sampled along the first well path, and generating the second proposed well vertex may include generating a location of the second wellhead proposed from the implicit stratigraphic function sampled along the second well path.  In several such embodiments, the sampling may include sampling at substantially regular depths along the first and second well paths.  In other such embodiments, the digital model may include a tetrahedron grid, and the sampling may include sampling at intersections between the first and second well paths and the faces of the tetrahedron grid.  In other such embodiments, sampling may include taking at least one sample near an intersection between the first or second well path and a discontinuity, fault, or conformal horizon defined in the digital model.  In several embodiments, after the generation of a second proposed well vertex on the basis of the determined value of the implicit stratigraphic function, a location of the proposed second well vertex can be automatically adjusted on the first and second petrophysical logs respectively associated with the first and second boreholes.  In several such embodiments, the automatic adjustment of the location of the proposed second wellhead may include the iterative disturbance of an offset or stretch / compression factor and the correlation of the first and second petrophysical logs. in a neighborhood of the proposed first and second well peaks.  [0034] In addition, in several embodiments, said at least one structural element may comprise a geological map of an intermediate geological horizon, and in several embodiments, the intermediate geological horizon is not used to constrain the numerical model before it is generated.  In several embodiments, the underground formation data may comprise a seismic image, the location in the volume concerned may correspond to a point in the seismic image, access to the digital model to determine the value of the seismic image. the implicit stratigraphic function may include determining the value of the implicit stratigraphic function at the point in the seismic image, and generating at least one structural element may comprise generating a surface or a plurality of points in the seismic image on the basis of the determined value of the implicit stratigraphic function.  In addition, in several embodiments, the determination of the location in the volume concerned may include the determination of a plurality of locations in the volume concerned, access to the numerical model to determine the value of the Implicit stratigraphic function may include determining the value of the implicit stratigraphic function for each of the plurality of predetermined locations and determining a remainder for each of the plurality of predetermined locations from the value determined for each of the plurality of predetermined locations. plurality of locations, and generating at least one structural element may comprise generating a surface or a plurality of points based on the determined value and a determined remainder for each of the plurality of locations.  In several embodiments, the remainder at one location can be calculated as the difference between the value of the implicit function at that location and an average (for example an average or an arithmetic, geometric, harmonic median), a representative value (by example a minimum, or a maximum) determined from values of the implicit function sampled at a plurality of locations, or as the difference between the value of the implicit function at that location and an arbitrarily selected value.  In several embodiments, this residue can be interpolated in a relevant volume containing the plurality of locations, and a refined, updated or corrected implicit function can be obtained by adding the interpolated remainder to the original implicit function.  In several embodiments, the interpolated value of the remainder may further be constrained to be zero at a plurality of locations determined by previously modeled or interpreted data (well peaks, seismic horizons, etc.). ).  In several embodiments, the interpolation can be performed by deterministic algorithms such as kriging, discrete linear interpolation, inverse distance, and so on.  In other embodiments, the remainder interpolation may be performed using a stochastic geostatistical algorithm such as sequential Gaussian simulation, Gaussian random function simulation, and the like. , allowing generation of a plurality of equiprobable interpolated residual cubes.  In several embodiments, this interpolation may be discontinuous across many of the faults and non-conforming surfaces.  In several embodiments, structural elements can be extracted from the refined, updated or corrected implicit function and from an average value of the implicit function determined from the plurality of entered locations.  Several embodiments may also comprise an apparatus comprising at least one processing unit and a program code configured during execution by said at least one processing unit to generate structural information for a subterranean formation of any of the ways discussed here.  Several embodiments may also include a program product comprising a computer readable medium and program code stored on the computer readable medium and configured at runtime by at least one processing unit to generate structural information for an underground formation in any of the ways discussed here.  Other variations and modifications will become apparent to those skilled in the art.  Hardware and Software Environment [0039] Referring now to the drawings, in which like numerals refer to similar parts in the different views, Figure 1 illustrates an example of a data processing system 10 in which different technologies and techniques described here can be implemented.  The system 10 is illustrated as comprising one or more computers 12, for example, client computers, each comprising a central processing unit (CPU) 14 comprising at least one hardware-based processor or one processing core 16 .  The CPU 14 is coupled to a memory 18, which may represent random access memory (RAM) devices comprising the main storage of a computer 12, as well as any additional levels of memory, for example, cache memories, memories nonvolatile or backup memory (for example, programmable or instant memory), read-only memories, etc.  In addition, the memory 18 may be considered as comprising a storage memory that is physically located elsewhere in a computer 12, for example, any cache memory in a microprocessor or a processing core, as well as any storage capacity used as virtual memory for example, stored on a mass storage device 20 or on another computer coupled to a computer 12.  Each computer 12 also generally receives a number of inputs and outputs to communicate information to the outside.  To interface with a user or an operator, a computer 12 essentially comprises a user interface 22 which incorporates one or more user input / output device (s), for example a keyboard, a pointing device, a display screen, printer, etc.  Otherwise, a user input may be received, for example, on a network interface 24 coupled to a network 26, from one or more external computer (s), for example, one or more servers (s) 28 or other computer (s) 12.  A computer 12 may also be in communication with one or more mass storage device (s) 20, which may be, for example, internal hard disk storage devices, external hard disk storage devices, storage network devices, etc.  A computer 12 operates essentially under the control of an operating system 30 and executes or otherwise bases itself on different computer software applications, components, programs, objects, modules, data structures. etc.  For example, a petrochemical module or component 32 operating within an Exploration and Production Platform (E & P) 34 may be used to access, process, generate, modify, or otherwise utilize petro-technical data. for example, stored locally in a database 36 and / or accessed remotely from a collaboration platform 38.  The collaboration platform 38 may be implemented using multiple servers 28 in several implementations, and it will be appreciated that each server 28 may incorporate a CPU (CPU), memory, and other hardware components similar to a computer 12.  In a non-limiting embodiment, for example, an E & P platform 34 can be implemented as a PETREL exploration and production (E & P) software platform, while the collaboration platform 38 can be implemented as the STUDIO E & P KNOWLEDGE ENVIRONMENT platform, both of which are available from Schlumberger Ltd.  and its subsidiaries.  It will be appreciated, however, that the techniques discussed herein may be used in connection with other platforms and environments, and therefore that the invention is not limited to the particular software platforms and environments discussed herein.  In general, the routines executed to implement the embodiments disclosed here, whether implemented as part of an operating system or as an application, a component, a program, an object a specific module or sequence of instructions, or even a subset thereof, will be referred to herein as "computer program code" or simply as "program code".  A program code essentially contains one or more instruction (s) that reside at different times in different memories and different storage devices in a computer, and that, when read and executed by one or more Hardware-based processing in a computer (eg, microprocessors, processing cores, or other hardware-based circuit logic) causes that computer to perform the steps that incorporate a desired functionality.  Furthermore, while embodiments have been described and will be described hereinafter in the context of fully functioning computers and computer systems, those skilled in the art will appreciate that the various embodiments can be distributed as a product. in a variety of forms, and that the invention applies equally regardless of the particular type of computer readable media used to actually perform the distribution.  [0044] Such computer readable media may include computer readable storage media and communication media.  Computer readable storage media are inherently non-transient, and may include volatile and nonvolatile media, and removable and non-removable media implemented in any information storage method or technology, such as computer readable instructions. , data structures, program modules or other data.  The computer-readable storage media may further include RAM, ROM, erasable programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), flash memory, or other memory storage technology. solid state, a CD-ROM, a DVD, or any other optical storage, magnetic cassettes, magnetic tape, magnetic storage disk or other magnetic storage devices, or any other medium that can be used to store information desired and to which the computer 10 can access.  The communication media may include computer readable instructions, data structures, or other program modules.  By way of example, and without limitation, the communication media may comprise wired media such as a wired network or direct wired connection, as well as wireless media such as acoustic, radio frequency, infrared, and other media wireless.  Combinations of all of the above may also be included within the scope of the computer readable media.  Different program codes described in the following can be identified on the basis of the application within which they are implemented in a specific embodiment of the invention.  However, it will be appreciated that any particular program nomenclature that follows is used solely for convenience, and thus the invention should not be limited to use only in a specific application identified and / or made implicit by that nomenclature.  Furthermore, given the infinite number of ways in which computer programs can be organized into routines, procedures, methods, modules, objects, and the like, as well as the different ways in which program functionality can be assigned among different software layers that reside within a typical computer (for example, operating systems, libraries, APIs, applications, applets, etc.). It will be appreciated that the invention is not limited to the specific organization and assignment of the program functionality described herein.  In addition, the skilled person benefiting from the present disclosure will appreciate the fact that the various operations described here that can be executed by any program code, or executed in all routines, all flow of operations, or the like, may be combined, split, reordered, omitted and / or added to other techniques known in the art and, therefore, the invention is not limited to the particular sequences of operations described herein.  Those skilled in the art will recognize that the exemplary environment illustrated in Figure 1 is not intended to limit the invention.  Indeed, those skilled in the art will recognize that other alternative hardware and / or software environments can be used without departing from the scope of the invention.  Oil Field Operations [0048] FIGS. 2A-2D illustrate simplified schematic views of an oil field 100 having an underground formation 102 containing a reservoir 104 in accordance with implementations of various technologies and techniques described herein.  Figure 2A illustrates a survey operation that is performed by a survey tool, such as a seismic truck 106. 1, to measure properties of the underground formation.

The survey operation is a seismic survey operation to produce sound vibrations. In FIG. 2A, a sound vibration of this type, the sound vibration 112 generated by a source 110, reproduces the horizons 114 in a terrestrial formation 116. A set of sound vibrations is received by sensors, such as receivers-geophones 118 , located on the surface of the earth. The received data 120 is provided as input to a computer 122.1 of a seismic truck 106.1, and in response to the input data, the computer 122.1 generates a seismic data output 124. This seismic data output can be stored, transmitted or reprocessed if desired, for example, by data reduction. FIG. 2B illustrates a drilling operation that is performed by drilling tools 106.2 suspended by a drilling rig 128 and advanced into underground formations 102 in order to form a wellbore 136. A sludge basin 130 is used. for harvesting the drilling mud in the drilling tools via a flow line 132 for driving the drilling mud down through the drilling tools, then up into the wellbore 136 and return it to the surface. The drilling mud can be filtered and returned to the sludge basin. A circulation system can be used to store, control or filter the flow of drilling mud. The drilling tools are advanced into subterranean formations 102 until they reach the tank 104. Each well may target one or more tank (s). The drilling tools are adapted to measure borehole properties using logging tools during drilling. The logging tools during drilling can also be adapted for sampling a core sample 133, as shown. Computer installations may be positioned at different locations around the oil field 100 (for example, the surface unit 134) and / or at remote locations. The surface unit 134 may be used to communicate with drilling tools and / or off-site operations, as well as with other surface or borehole sensors. The surface unit 134 is capable of communicating with the drilling tools to send commands to the drilling tools, and to receive data therefrom. The surface unit 134 may also collect data generated during the drilling operation and produce a data output 135, which may then be stored or transmitted. [0051] Sensors (S), such as gauges, may be positioned around the oil field 100 to collect data relating to different oil field operations, as previously described. As shown, the sensor (S) is positioned in one or more locations in the drill tools and / or drill bit 128 to measure drilling parameters, such as the weight on the drill bit. , the torque on the bit, the pressures, the temperatures, the flow rates, the compositions, the rotational speed and / or other parameters of the field operation. The sensors (S) can also be positioned in one or more places in the circulation system. The drill bits 106.2 may comprise a bottom hole assembly (BHA) (not shown), generally referenced near the bit (for example, within several drill collar lengths). from the trephine). The downhole assembly includes capabilities for measuring, processing, and storing information, as well as for communicating with a surface unit 134. The downhole assembly further includes drill collars for performing various other measured. The downhole assembly may comprise a communication subassembly that communicates with the surface unit 134. The communication subassembly is adapted to send signals to and receive signals from the surface using a communication channel such as mud pulse telemetry, electromagnetic telemetry, or wired drill pipe communications. The communication subsystem may include, for example, a transmitter that generates a signal, such as an acoustic or electromagnetic signal, that is representative of the measured drilling parameters. Those skilled in the art will appreciate that a variety of telemetry systems may be employed, such as a wired drill pipe, an electromagnetic system or other known telemetry system. In general, the wellbore is drilled according to a drilling plan that is established before drilling. The drilling plan specifies the equipment, pressures, trajectories and / or other parameters that define the drilling process for the drilling site. The drilling operation can then be performed according to the drilling plan. However, when information is collected, the drilling operation may need to deviate from the drilling plan. In addition, when drilling or other operations are performed, subterranean conditions may change. The terrestrial model may also need adjustment when new information is collected. The data collected by the sensors (S) may be collected by the surface unit 134 and / or other data collection sources to perform analysis or other processing. The data collected by the sensors (S) can be used alone or in combination with other data. The data may be collected in one or more database (s) and / or transmitted on-site or off-site. The data may be historical data, real-time data, or combinations thereof. Real-time data can be used in real time, or stored for later use. The data can also be combined with historical data or other inputs for further analysis. Data can be stored in separate databases, or combined into a single database. The surface unit 134 may comprise a transceiver 137 to allow communications between the surface unit 134 and different parts of the oilfield 100 or other locations. The surface unit 134 may also be provided with or operably connected to one or more control devices (not shown) for operating mechanisms on the oil field 100. The surface unit 134 may then send control signals to the oil field 100 in response to received data. The surface unit 134 may receive commands through the transceiver 137 or may itself execute commands on the controller. A processor may be provided for analyzing data (locally or remotely), making decisions, and / or operating the controller. In this way, the oil field 100 can be selectively adjusted based on the collected data. This technique can be used to optimize parts of the field operation, such as controlling a drill, the weight on the bit, pump speeds or other parameters. These adjustments can be made automatically on the basis of a computer protocol, and / or manually by an operator. In many cases, well plans can be adjusted to select optimal operating conditions, or to avoid problems. FIG. 2C illustrates a cable work operation performed by a cable work tool 106.3 suspended by a drilling rig 128 and in a wellbore 136 of FIG. 2B. The cable working tool 106.3 is adapted to be deployed in the wellbore 136 for generating well logs, performing borehole tests, and / or collecting samples. The cable working tool 106.3 may be used to provide another method and apparatus for performing a seismic survey operation. The cable working tool 106.3 may, for example, include an explosive, radioactive, electrical, or acoustic energy source 144 that sends and / or receives electrical signals to surrounding subterranean formations 102 and fluids therein. The cable working tool 106.3 may be operatively connected, for example, to geophones 118 and a computer 122.1 of a seismic truck 106.1 of Figure 2A. The cable working tool 106.3 can also provide data to the surface unit 134. The surface unit 134 can collect the data generated during the cable operation and can produce a data output 135 which can to be stored or transmitted. The cable working tool 106.3 may be positioned at different depths in the wellbore 136 to provide a survey or other information relating to the underground formation 102. [0059] Sensors (S), such as gauges, can be positioned around the oil field 100 to collect data relating to different field operations, as described above. As shown, the sensor S is positioned in the cable work tool 106.3 to measure borehole parameters that are relative to, for example, porosity, permeability, fluid composition, and / or other parameters of the field operation. FIG. 2D illustrates a production operation that is executed by a production tool 106.4 deployed from a production unit or a Christmas tree 129 and in a completed wellbore 136 to suck a fluid at From the borehole reservoirs in surface facilities 142. The fluid flows from the reservoir 104 through perforations in the sheath (not shown) and in the production tool 106.4 in the wellbore 136 and to the surface facilities 142 via a collection network 146. [0061] Sensors (S), such as gauges, may be positioned around the oil field 100 to collect data relating to different operations. field as described above. As shown, the sensor (S) can be positioned in the production tool 106.4 or in associated equipment, such as a Christmas tree 129, a collection network 146, a surface installation 142 and / or the production facility for measuring fluid parameters, such as fluid composition, flow rates, pressures, temperatures and / or other parameters of the production process. The production may also include injection wells for increased recovery. One or more collection facilities may be operatively connected to one or more of the drilling sites to selectively collect borehole fluids from the site (s) of the wellsite (s). drilling. Although FIGS. 2B to 2D illustrate tools used to measure properties of an oil field, it will be appreciated that the tools can be used in connection with non-oil operations, such as gas fields, mines, aquifers, storage or other underground facilities.

Similarly, while some data acquisition tools are described, it will be appreciated that different measurement tools capable of detecting parameters, such as two-way seismic travel time, density, resistivity, production, etc., of the underground formation and / or its geological formations may be used. Different sensors (S) may be located at different positions along the wellbore and / or monitoring tools to collect and / or monitor the desired data. Other sources of data may also be provided from offsite locations. The field configurations of FIGS. 2A-2D are intended to provide a brief description of an example of a usable field with oilfield application frameworks. Some or all of the oil field 100 may be on land, on water, and / or at sea. Similarly, while a single field measured at a single location is described, oil field applications may be used with any combination of one or more oilfield (s), treatment facility (s) and drilling site (s). FIG. 3 is a diagrammatic view, partially in cross-section, of an oil field 200 presenting data acquisition tools 202.1, 202.2, 202.3 and 202.4 positioned at different locations along the oil field 200 for collecting data. underground formation data 204 according to an implementation of different technologies and techniques described herein. The data acquisition tools 202.1-202.4 may be the same as the data acquisition tools 106.1-106.4 of Figures 2A to 2D, respectively, or others not described. As shown, the data acquisition tools 202.1-202.4 generate data traces or measurements 208.1-208.4, respectively. These data plots are described along the oil field 200 to demonstrate the data generated by the different operations. The data traces 208.1-208.3 are examples of static data plots that can be generated by the data acquisition tools 202.1-202.3, respectively, however, it should be understood that the data plots 208.1-208.3 can also be data plots that are updated in real time. These measurements can be analyzed in order to better define the properties of the formation (s) and / or to determine the accuracy of the measurements and / or to search for errors. The plots of each of the respective measurements can be aligned and proportioned for comparison and property verification purposes. The static data plot 208.1 is a two-channel seismic response over a period of time. Static plot 208.2 shows core sample data measured from a core sample of formation 204. The core sample can be used to provide data, such as a graph of density, porosity, permeability, or several other physical properties of the core sample over the length of the core. Density and viscosity testing can be performed on fluids in the core at varying pressures and temperatures. Static data plot 208.3 is a logging trace that essentially provides a measure of resistivity or other measure of formation at different depths. A curve or graph of the decline in output 208.4 is a dynamic data plot of fluid flow versus time. The decline in production curve provides essentially the speed of production as a function of time. As the fluid flows through the wellbore, fluid property measurements are made, such as flow rates, pressures, composition, and the like. Other data may also be collected, such as historical data, user inputs, economic information, and / or other measurement data and other relevant parameters. As described below, static and dynamic measurements can be analyzed and used to generate models of the subterranean formation to determine its characteristics. Similar measurements can also be used to measure changes in the aspect of training over time. The underground structure 204 has a plurality of geological formations 206.1-206.4. As shown, this structure comprises several formations or layers, comprising a shale layer 206.1, a carbonate layer 206.2, a shale layer 206.3 and a sand layer 206.4. A fault 207 extends through the shale layer 206.1 and the carbonate layer 206.2. Static data acquisition tools are suitable for performing measurements and detecting characteristics of formations. Although a specific subterranean formation having specific geological structures is described, it will be appreciated that the oilfield 200 may contain a variety of structures and / or geological formations, sometimes with extreme complexity. In many places, usually below the water line, a fluid can occupy the pore spaces of the formations. Each of the measuring devices can be used to measure properties of the formations and / or its geological characteristics. While each acquisition tool is shown as being in specific locations in the oil field 200, it will be appreciated that one or more types of measurements may be performed at one or more locations through one or more field (s) or other location (s) for comparison and / or analysis purposes. The data collected from different sources, such as the data acquisition tools of Figure 3, can then be processed and / or evaluated. In general, the seismic data displayed in the static data plot 208.1 from the data acquisition tool 202.1 is used by a geophysicist to determine the characteristics of the subterranean formations and the features. The core data shown in static plot 208.2 and / or logging data from well logging 208.3 is primarily used by a geologist to determine the different characteristics of the subterranean formation. The production data from Chart 208.4 is primarily used by reservoir engineering to determine the characteristics of the fluid flow reservoir. The data analyzed by the geologist, the geophysicist and the reservoir engineering can be analyzed using modeling techniques. Figure 4 illustrates an oil field 300 for performing production operations according to the implementation of different technologies and techniques described herein. As shown, the oilfield includes a plurality of drilling sites 302 that are operatively connected to a central processing facility 354. The oilfield configuration of Figure 4 is not intended to limit the scope of the oil field. of the oil field application system. Some or all of the oil field may be on land and / or at sea. Similarly, while a single oil field with only one treatment facility and a plurality of drilling sites is described, any combination of one or more oil field (s), treatment facility (s) and one or more drilling site (s) may be present. Each drilling site 302 includes equipment that forms a wellbore 336 in the earth. The wells extend through subterranean formations 306 including reservoirs 304. These reservoirs 304 contain fluids, such as hydrocarbons. The drilling sites draw fluid from the tanks and transmit it to the processing facilities via surface networks 344. Surface networks 344 include production and control column mechanisms to control the flow of fluids. from the drilling site to the treatment plant 354. Generation of structural elements for underground formation using an implicit stratigraphic function Embodiments consistent with the invention can be used to generate structural information for an underground formation on the basis of an implicit stratigraphic function of a structural framework of modeling based on the volume of the underground formation. In an embodiment discussed below, for example, an interactive method may be used in connection with a well correlation to determine well vertices that correspond to the intersection of multiple wellbore holes with a geographic layer ( or horizon that represents this one). The embodiments discussed in the following will focus primarily on well correlation, as well as on an interactive method; however, as will become more clearly apparent below, the invention may also be used in connection with the determination of other structural elements in a subterranean formation, as well as in non-interactive methods.

Therefore, the invention is not limited solely to the interactive correlation of well applications discussed in detail here. As indicated above, well vertices are traditionally interpreted at the intersection of a well path and the boundary between two geological layers (i.e., a geological horizon). A conventional method for interpreting wellheads is based on the search for large variations in petrophysical properties (eg, porosity) that reveal a change in the geologic facies of the rocks penetrated by the borehole of a well. The method of identifying / recognizing a given geological horizon along a plurality of wells is generally referred to as a well correlation, and this method is based primarily on a set of petrophysical logs (eg, porosity neutron). , gamma rays, etc.) and the search for similar models, that is, types of variations, on the different logs. To facilitate correlation, an iterative approach can be employed, where the most obvious stratigraphic interfaces are first identified, and are then used as a reference to correlate the less obvious interfaces. For example, a well correlation can be performed by displaying all well tracks and associated logs side by side in a single graphics window on a computer, manually adjusting the offset, scale, and stretching. local logs displayed so that reference markers are "flattened" to the same reference depth for all logs, and then using a "real stratigraphic thickness" (i.e., a perpendicularly measured thickness geological layers) to visualize the depth of both logs and well markers. However, in the presence of horizontal wells that alternate between up-dip and down-dip, and / or in the presence of geological faults intersecting wells, it may be difficult to accurately calculate the "true stratigraphic thickness" of the wells. 'a geological layer. In addition, not all petrophysical logs can have been measured in all wells, and confidence in well logs may be affected by the fact that the observed petrophysical "models" generally become more dissimilar when the distance between wells increases. In some cases, the well correlation is integrated with a three-dimensional modeling (3D) of the reservoir, and follows a cascading linear process from well-well interpretation and correlation (which are essentially performed). based on the observation of petrophysical logs), the creation of a 3D model that integrates geometric and stratigraphic information provided by the wells to adjust the geometry of 3D horizon surfaces. The integration of information from the 3D model into the well correlation method is generally much more complex.

In particular, the integration of information on the intermediate horizons, ie the horizons situated between seismically interpreted horizons, essentially involves the construction of a 3D reservoir grid (for example, a grid with points angle) from which the intermediate horizon can be extracted, so that the intersection between this intermediate horizon and the wells can be calculated. The 3D grid manufacturing process can involve intensive user interactions and excessive simplification of the entered model, which can also have a negative impact on the geometry of the extracted horizons. In several embodiments consistent with the invention, on the other hand, the well correlation can be performed in an interactive manner based on stratigraphic information contained in a structural framework model constructed using a VBM technology (volume-based modeling). This makes it possible to effectively know the relative stratigraphic age substantially through a relevant volume in a subterranean formation for use in the well correlation method. In several embodiments, this allows for a tighter loop between well-peak extraction and correlation and modeling, since new wells can be extracted directly from the structural framework. VBM technology can be used to directly model volumes (eg, geologic layers) rather than surfaces (for example, horizons that are contiguous geographic layers). The approach is essentially based on the concept of "implicit modeling", in which surfaces are represented as iso-values of a volume attribute generally referred to as the implicit function. The volume attribute can be defined through a relevant volume and can represent the stratigraphic age of the formation. As illustrated in Figure 5, a structural frame 320 may be initially defined by faults 322 and horizons 324, determined, for example, through seismic surveys, or other known ways. A tetrahedron gate 326 is constituted, constrained by the existing faults 322 and horizons 324, to carry the implicit function. Then, the values of the implicit function are interpolated on the nodes of the tetrahedron grid, as shown by the shading at point 328. Using an iso-surfacing algorithm, an implicitly modeled surface can then be generated for each horizon, resulting in a coherent zone model for global underground formation. The implicit function makes it possible to fabricate structural models on the basis of a tetrahedron grid constrained by the input data (for example, interpretations of faults, well vertices and / or horizons). These models can be used as a starting point for the construction of 3D tank grids.

However, a limitation imposed by these models is that the extraction of additional horizons essentially required that the horizon modeling process be repeated with additional input data (for example, a single well vertex), which can be impractical and time consuming.  In general, the existing extraction method does not allow, for example, the interactive generation, in real time or practically in real time, of a coherent fault horizon surface that passes through a selected point so arbitrary.  For example, as illustrated by the flow of operations 400 of FIG. 6, well correlation consistent with several embodiments of the invention can be performed to determine well vertices 402 in a manner that interactive and in conjunction with the realization of a Volume Based Modeling (VBM) 404 framework (based on wells 402 as well as additional input data 406 such as interpreted faults and horizons) across the introduction of an interactive wellhead extraction operations flow 408.  Note that the interactive method can be executed before the generation of a 3D tank grid 410, unlike several existing flow operations.  Figure 7 illustrates additional details of an exemplary flow of operations 420 consistent with several embodiments of the invention.  Initially, a set of interpreted wells 422 may be accompanied by a set of initial interpreted wells 424, for example, well peaks determined through obvious correlations seen in well logs.  A VBM structural framework 426 can then be constructed from interpreted well vertices 422 and interpreted seismic data 428 (for example, including faults and / or horizons).  On the basis of the VBM structural framework, a graphical representation of the subterranean formation data is generated and displayed to a user (block 430).  The graphical representation may include any appropriate graphical display of relevant subterranean formation data, for example, a 2D or 3D display of the VBM structural framework with representations of the well paths of all existing and / or proposed wells, a set of well tracks. (ie, well logs oriented along a vertical axis that corresponds to a depth), etc.  Then, a user can point to a new reference well vertex (block 432) from the graphical representation, resulting in the generation of one or more new proposed well top (s). corresponding (s) (block 434) and automatically integrating the new well vertices proposed on the graphical representation, for example by superimposing graphical representations of the new well vertices on the graphical representation of the formation data underground (block 436) .  Then, at block 438, the user can review the positions of the vertices of wells added automatically to the active / selected wells and validate, modify and / or delete the interpolated well vertices.  Well peaks can also be renamed in several embodiments.  A tool such as Visual QC, available from Schlumberger Ltd.  and its affiliates, can be used to automatically validate or delete the added wellheads.  In several embodiments, validated well vertices may be signaled such that they are consumed by modeling algorithms, while unverified vertices may be ignored during construction of the 3D model.  Then, at block 440, the validated well vertices may be added to the set of interpreted well vertices 422 to be used for the modeling and to the inputs of the VBM structural frame 426.  In addition, validated well vertices can be added to any stratigraphic column displayed in a graphical representation.  The operations mentioned above can also be repeated, thereby allowing a user to interactively generate new well vertices.  In addition, as illustrated in block 442, manual editing of the well peaks can be performed, for example, to adjust the locations of the new wellheads proposed from the locations initially generated.  For example, in a number of embodiments, the proposed new well vertices may be superimposed on the well tracks, and a user may align the calculated well vertices with their most likely actual location along the well tracks, for example, based on a correlation between the well logs of the original reference wells and the corresponding well logs on other active / selected wells.  In addition, in several embodiments, all vertices edited manually can be considered "validated" by the user.  In one embodiment, for example, an interactive well correlation tool or module, for example implemented as a petro20 technical module 32 of an E & P platform 34 (FIG. 1), may be used. to perform interactive wellhead extraction as disclosed herein.  In such an embodiment, and as shown in FIG. 8, a user may be presented with a graphical representation 450 of a series of well tracks (for example, well tracks 452 and 454) that display well logs of a plurality of wells.  Existing well vertices may be represented as shown at 456 and 458, for example, including an identifier or name for the well top (e.g., identifiers 456a and 456b), a horizontal line segment ( for example, the line segments 456c and 456d) which correspond to the depth of the well vertex in each well track 452, 454, and an additional line segment 456e which graphically connects the horizontal line segments 456c, 456d in order to visually represent the correspondence of the two wells.  As illustrated in the upper half of Figure 8, a user can position a mouse pointer 460 at a desired location on the graphical representation 450, which corresponds to a particular depth for a reference well represented by the track. wells 452, and therefore at a particular place in the underground formation.  Then, by a click or other indication by the user of the selection of the desired location (shown at 462), both a graphical representation 464 of the well vertex selected on well track 452 for the well of reference, and a graphical representation 466 of a corresponding proposed new well vertex on well track 454, may be displayed.  Note that the graphical representations 462, 464 may include identifiers and horizontal line segments joined by a link line segment, similar to that described above for the graphical representation 456.  [0093] Other ways of visually representing a well top may be used in other embodiments.  For example, when a 3D or 2D representation of a subterranean formation is displayed, and well paths are displayed for the wells in the subterranean formation, well peaks may be represented by markers at associated depths along the graphical representations of well roads.  A well top can also be displayed in a map or stereonet.  To display it in a stereotype, for example, a dip angle and a dip azimuth can be extracted from the implied function at the well top position (the dip angle and the dip azimuth can be extracted, for example, from the gradient of the default function).  In several embodiments, the display of well vertices may occur before a user clicks on a particular location on a graphical representation.  For example, in several embodiments, each time a user moves a mouse cursor on a given well track (which corresponds to a reference well), a "phantom" well vertex can be displayed at the corresponding depth. of the mouse on the well track on which the mouse is located, and the corresponding well top (s) on other active wells and / or selected in a project can similarly be displayed as vertices of additional "ghost" wells.  Moving a mouse pointer at different depths along a reference well track may result in corresponding dynamically updated corresponding well vertex positions to follow the change in depth.  Then, by clicking on or selecting a particular location, the "ghost" pit vertices can change their appearance to represent the user's selection of the location.  It will be appreciated that other graphical representations can be used to indicate well vertex positions in a graphical representation of subterranean formation data, essentially based at least in part on the type of subterranean formation data, such as E & P platform and other factors that will be apparent to a skilled person benefiting from this disclosure.  Referring to Figure 5, as indicated above, the correspondence between the well tracks may be based at least in part on the relative stratigraphic time information contained in a structural framework or a VBM model.  The VBM structural frame can be configured as a coarse tetrahedron solid associated with a set of triangular thin surfaces that represent geological horizons, and the "relative stratigraphic time" information can be represented as illustrated in point 328 by the combination of a "stratigraphic" property stored at the nodes of the tetrahedron grid and interpolated linearly within each tetrahedron, associated with an "offset" which corresponds to the difference between the fine scale surfaces and the coarse tetrahedron grid.  Referring now to Figure 9, this figure illustrates routine example 470 for extracting corresponding well vertices based on an implicit stratigraphic function.  As shown in block 472, to allow interactive well correlation, the implicit stratigraphic function of a VBM structural framework (ie, relative stratigraphic age) can first be sampled along each well road, and be associated with different wells (eg as a new well log).  Different sampling strategies can be used in different embodiments.  For example, samples may be taken at regularly spaced intervals along the measured depth, and / or samples may be taken at intersections between a well path and the faces of the tetrahedron grid.  In addition, in several embodiments, additional samples may be added at intersections between wells and discontinuities such as faults and non-conformities and / or at intersections with conformal horizons.  The relative stratigraphic age can then be interpolated, for example linearly, between the different samples (block 474).  In addition, in several embodiments, the relative stratigraphic age gradient can be sampled from a 3D volume on the well logs.  Then, the location of well vertices along selected / active well paths is performed in response to the user's input by determining, from the sampled data, the value of the function implicitly assigned to it. location (depth) of the mouse pointer along the well path of the reference well (block 476), i.e., within the graphical representation of the subterranean formation data corresponding to the reference wells.  It will be appreciated that a reference well may be statically defined, such that all user inputs in connection with the extraction of the well peaks are directed to the graphical representation of the subterranean formation data for this well.  In other embodiments, however, the reference well may be dynamic and may be considered to be the well associated with the graphical representation with which the user interacts at any given time.  Then, at block 478, the places that correspond to the same value of the implicit function (or at least within a range of the value of the implicit function) are then used to generate structural elements, for example, wells for each other well concerned (eg, all visible wells, all selected wells, all active wells, etc.). ).  Graphical representations of the structural elements are then generated and displayed with the graphical representations of the subterranean formation data corresponding to each other well concerned at block 480.  It will be appreciated that there may be zero or more corresponding locations on any of the other relevant wells depending on the geometries of these wells.  The routine 470 can be interactive by nature and, therefore, if the user wishes to extract additional well vertices, the block 482 passes the command back to block 476 in order to receive an additional input from a user who specifies another location along a well road.  When the user has finished extracting the well vertices, block 482 completes routine 470.  [00102] As also indicated above in connection with block 436 of FIG. 7, it may be desirable in several embodiments to additionally perform automatic integration on well logs, for example, logs. after proposing new well vertices in the manner described above in connection with Figure 9.  In some cases, the generation of a well vertex based exclusively on the value of an implicit function can identify a location that is close to the optimum position of the well top along the well, but through further refinement. in order to integrate the local variations of the relative thicknesses of the geological layers, a more precise location can be determined.  In several embodiments, such an adjustment may be performed automatically by finding the offset and the stretching / compression factor on the target well for which the model defined by a selected petrophysical well log (or multiple logs) is most similar to the models observed on the reference well.  For example, in one embodiment, the base shift can be provided by the location of the "initial estimate" well top, which corresponds to the location on the treated well for which the relative stratigraphic age same as the user-selected location of the reference well vertex on the reference well.  The basic stretching / compression factor between the reference well and the treated well can be given by the ratio of the gradients of the implicit function to the reference and corresponding well vertices.  The adjustment can then incorporate an iterative optimization method where the value of the offset and / or the stretching / compression factor are slightly disturbed, and a local search is performed for the optimal correlation between the petrophysical logs on the reference well and the well selected in the vicinity of the reference / corresponding well peaks.  Once an optimal local correlation is found, the new offset value can then be used to update the position of the corresponding well top on the treated well.  The process can then be repeated on each other well concerned.  In this method, the inputs may include: - a maximum offset value (in MD), expressed as the absolute value of the difference with the base offset.  In the case where the distance between the processed vertex and a previously validated vertex is less than the maximum offset value, the maximum offset value will be automatically reduced; a maximum stretching / compression factor, expressed as the absolute value of the difference with the basic stretching / compression factor; and a length of the window considered for the correlation (on the reference well).  The method can then try to minimize a cost, so that: the cost increases with the difference between the offset and the stretch calculated and the offset and the base stretch; the cost decreases with the similarity of the logs on the reference well and the treated well; and - the cost is a weighted sum of the calculated costs of each of the entered petrophysical logs.  The weights can be deduced from the correlation computation between these logs along a window around all vertices interpreted manually (for example, the "initial interpreted wells" referred to in block 424 of Figure 7).  [00106] Different techniques for calculating optimal correlation and / or offset / stretching (for example, by dynamic time alignment, convolution, approximation by trigonometric polynomials or wavelets, etc.). ) may be used, as will be appreciated by those skilled in the art benefiting from this disclosure.  [00107] As indicated above, the iterative method described herein can be used to generate different types of structural information for underground formation in several embodiments of the invention.  For example, in several embodiments, intermediate horizon surfaces (i.e., horizons not initially used to constrain the construction of the VBM structural framework) may be extracted using the techniques described herein to generate a or more geological map (s) (that is, faulty surfaces).  In particular, surfaces that correspond to iso-values of the relative stratigraphic time can be interactively extracted from the VBM structural framework, for example, in the form of triangular surfaces, and be visually represented as geological maps.  The surfaces may be such that they pass through an existing or new set of wells and / or subdivide a given stratigraphic gap into an arbitrary number of sub-intervals of equal real stratigraphic thickness.  In other embodiments, the iterative method described herein may be used in connection with a guided seismic horizon interpretation, so that instead of using well paths and / or logging logs, Wells, traces of seismic wells can be considered and used to construct new objects of "horizon interpretation" or "geological layer" seismic attributes that represent seismic events from the implicit function.  As illustrated by routine 500 of Figure 10, for example, well traces can be correlated by first "painting" the implicit stratigraphic function on a seismic cube at block 502, for example, by interpolating the implicit function. from the node or voxel tetrahedron grid of the seismic cube (for example, using a linear least squares formulation based on the barycentric coordinate of the seismic node in the tetrahedron containing this node).  Next, at block 504, a reference correlation (offset and stretch) between neighboring well traces may be generated based on the implicit function to provide an initial estimate for correlating neighboring well traces.  [00109] Next, in response to an input from the user, for example, a mouse click, the value of the implicit function at the location of the mouse pointer along a reference well trace ( representing a time / depth in the well trace) is determined (block 506).  Then, at block 508, the locations that correspond to the same value of the implicit function (or at least within a range of the value of the implicit function) are then used to generate structural elements, for example, horizon interpretation objects, which represent corresponding seismic events for other traces of relevant wells (for example, all visible well traces, all traces of neighboring wells, all selected well traces, all traces of active wells, etc. ).  Graphic representations of the corresponding structural elements (objects) are then generated and displayed with the graphical representations of the well traces at block 510.  Block 512 can then determine if the user has completed the seismic interpretation, and if not, returns to block 506.  However, if no further interpretation is to be performed, routine 500 is performed.  [00110] More generally, the routine 500 may be considered useful for generating structural elements such as a surface or a plurality of points in a seismic image, for example, a seismic cube, based on a determined value of a stratigraphic implicit function correlated to a location in a relevant volume based on a selected point in the seismic image.  In several embodiments, for example, each iso-value of a relative stratigraphic age attribute (AGR) may be considered potentially corresponding to a geological horizon, i.e. interface between two geological layers.  The AGR attribute can be used to guide seismic interpretation, for example, visually through an interactive method, or as an additional constraint when performing seismic self-tracking.  Conventionally, self-tracking is performed by comparing neighboring seismic traces and searching for the optimal vertical offset which has a maximum similarity between these traces in the vicinity of a given seismic horizon, with the optimal offset selected on the basis of of the offset value itself (which may be constrained to be consistent with a pre-calculated local dip), the value of the "similarity" (i.e., correlation) between the seismic traces a once the offset has been removed, and the limited stretch / compression that can also be applied to the traces in order to maximize similarity.  However, when an implicit function attribute / AGR is used to guide self-tracking, the AGR attribute can provide both a reference offset (for example, based on the dip of the chosen surface) and a reference stretching / compression (eg, based on gradient difference) for similarity search.  In addition, the AGR attribute can be used to correlate traces across faults.  Furthermore, in several embodiments, when a seismic scale AGR attribute has been calculated, it may also be possible to simply "align" iso-surfaces of the attribute to the nearest peak, passing by a zero crossing of the seismic signal on each trace in order to obtain an automatic interpretation without resorting to self-tracking.  In other embodiments, structural elements can be generated based on scarce data.  In these embodiments, instead of extracting an iso-value directly from the implicit function, a value extracted from the implicit function can be combined with a leftover value (also referred to herein as a "remainder"), or an implicit function that has been updated.  In these embodiments, rather than determining the location of a single location in the relevant volume, a set of locations (e.g., a set of well peaks that correspond to the same horizon) can be determined and used to generate a surface or a plurality of points based on both the values of the implicit function and the remainder values for the set of locations.  The relative geological age attribute can be used to replace the isochoric or isopach based flow of operations when calculating a geologically coherent structural model of a subterranean formation.  In particular, it can be used to interpolate the position of geological interfaces defined by rare and / or incomplete data (for example, wells).  In the process, the relative geological age attribute itself can even be updated taking into account the rare data.  In one illustrative embodiment, the general method for integrating rare data into the model can be as follows.  [00114] In the first place, a remainder can be calculated between an initial estimate of the relative geological age (AGR) and an attribute that would incorporate the scarce data, for example, by calculating the relative geological age from dense interpretations. only (that is, an initial estimate), for each horizon on the basis of the scarce data, by estimating the relative geological age (for example, by calculating the average of the values from the initial estimate to the location of the rare data) and, at each point of rare data, calculating a balance between the estimated AGR and the initial estimate, and interpolating the remainder with the following constraints (each of which can be represented as a set of linear equations).  [00115] Accept the remainder value calculated above at the location of the rare data points, either for one horizon at a time, or for all the horizons together; - to force a nil residue in the place of dense interpretations; - Optionally, force a zero balance away from all data, or in fault blocks that do not contain data; - Optionally, force a zero balance on the internal or external boundaries of the model; - ensure the smoothness of the remainder (for example through the application of a harmonic constraint); and - ensure the smoothness of [residual + initial estimate] and its gradients (for example, through a smooth gradient constraint, with the "unknown" values that are those of the remainder).  Then, the remainder can be added to the initial estimate to obtain the final value of the relative geological age, from which the iso-surfaces that correspond to the rare data can be extracted, or the dense reference data can be extracted. be moved and used to re-calculate an implicit function.  In the latter case, the remainder can be added to the initial estimate, and the relative geological age of an arbitrary reference horizon defined by a dense interpretation can be subtracted.  The calculated difference and gradient of [initial estimate + remainder] can be used to calculate a 3D shift (ie a vector field) that would move all points of the reference horizon to the target surface.  An offset point can be created using the dense reference interpretation plus the calculated vector field.  The operations listed above can then be repeated for each horizon based on the scarce data.  A final implicit function can then be calculated based on the original data points and offset points.  As illustrated by routine 520 of Figure 11, for example, rare data may be integrated into a model in one embodiment by first selecting a plurality of locations for the purpose of new structural elements from a model (block 522).  In different embodiments, for example, locations (eg, wells, seismic points, etc.) are provided. ) can be selected interactively from a graphical representation of underground data, or automatically, for example by applying a combination of filters on the available input data.  Then, at block 524, an implicit function can be sampled, or interpolated, at these different locations, producing a scalar value (e.g., relative geological age) by location.  A mean or representative value (for example a median, an arithmetic mean, etc.) ) can be calculated from the sampled or interpolated values (block 526), and for each selected point, a "leftover" value can be calculated (block 528), for example, by subtracting the average or representative value from the value initially sampled or interpolated at block 524.  The remainder calculated in block 528 can then be interpolated in the volume concerned, for example, using a stochastic (for example, sequential Gaussian simulation) or deterministic (for example, a kriging) interpolation technique (block 530 ).  In several embodiments, additional data points (e.g., well peaks, seismic interpretation points, etc.) are provided. ) can also be used to constrain the remainder to a value of zero at more than one point in the model.  The resulting "remainder" can be considered as an attribute or a scalar property, whose value is known, or can be calculated, in the entire volume concerned.  Then, in block 532, an updated implied function can be calculated from the initial implicit function and the remainder, for example, by summing scalar values of the initial implicit function and the remainder to produce a new field. scalar value, for example, defined at the nodes of a 3D grid.  New structural elements, for example, new horizon surfaces, new seismic interpretation points or new wells, etc. , can then be extracted from the updated implied function (block 534).  For example, in several embodiments, the average or representative value calculated at block 526 can be extracted as a surface using an isosurface algorithm, or as a set of new well peaks by locating the corresponding iso-values on a surface. or several well traces.  [00121] It will be appreciated that the techniques disclosed herein may be used in other applications to correlate other types of subterranean formation data, and therefore the invention is not limited to the particular applications disclosed herein.  In addition, while particular embodiments have been described, it is not intended that the invention be limited thereto, since the invention is intended to have a fairly broad scope as the art allow it and that the booklet should be read in that spirit.  Those skilled in the art will therefore appreciate that further modifications could be made without deviating from the spirit and scope so claimed. 10

Claims (15)

REVENDICATIONS1. A method of generating structural information for a subterranean formation containing extractable hydrocarbons, wherein the structural information is for use during exploration and production phases, the method comprising the steps of: determining a location in a relevant volume in the underground formation from underground formation data associated with underground formation; accessing, by means of at least one hardware-based processing unit 10 of a computer, a numerical model having a monotonically varying stratigraphic implicit function defined within the volume concerned to determine a value of the implicit function stratigraphic that corresponds to the determined location; and generating, by means of said at least one hardware-based processing unit of a computer, at least one structural element for the subterranean formation from the implicit stratigraphic function of the numerical model on the basis of a spatial distribution of the value determined within the volume concerned. 20 The method of claim 1, further comprising: receiving a user input directed to a graphical representation of subterranean formation data, wherein determining the location in the relevant volume includes determining the place on the basis of the entry of the user; and performing a graphical representation of said at least one structural element to be displayed in the graphical representation of the subterranean formation data. The method of claim 2, wherein: the graphical representation of subterranean formation data comprises a graphical representation of subterranean formation data for each of first and second boreholes formed in the subterranean formation; the user input includes user selection of a first proposed well vertex for the first borehole on the graphical representation of subterranean formation data for the first borehole; the location in the volume concerned includes a depth along the first wellbore that corresponds to the user's selection of the first proposed wellhead; accessing the numerical model to determine the value of the implicit stratigraphic function includes determining the value of the implicit stratigraphic function at the depth along the first borehole; the realization of at least one structural element includes generating, for the second borehole, a second proposed well top that corresponds to the first well vertex proposed for the first borehole based on the determined value of the implicit stratigraphic function; and driving said at least one structural element to be displayed in the graphical representation of the subterranean formation data comprises performing a graphical representation of the second proposed well vertex to be displayed on the graphical representation of subterranean formation data for the second hole drilling. The method of claim 3, wherein the graphical representations of the subterranean formation data for the first and second boreholes each comprise a well bore of a well log or a well path in a three-dimensional view. A method according to any one of the preceding claims, wherein: the subterranean formation data comprises subterranean formation data for each of the first and second boreholes formed in the subterranean formation, the location in the volume concerned comprises a depth along the first wellbore which corresponds to a first wellhead proposed for the first borehole; accessing the numerical model to determine the value of the implicit stratigraphic function includes determining the value of the implicit stratigraphic function at the depth along the first borehole; and generating at least one structural element comprises generating, for the second borehole, a second proposed well vertex that corresponds to the first proposed well vertex for the first borehole based on the determined of the implicit stratigraphic function. The method of claim 5, further comprising sampling the implicit stratigraphic function along each of first and second well paths respectively which correspond to the first and second boreholes, in which access to the digital model. for determining the value of the implicit stratigraphic function includes determining the value from the implicit stratigraphic function sampled along the first well path, and wherein generating the second proposed well vertex includes generating a location of the second well vertex proposed from the implicit stratigraphic function sampled along the second well path. The method of claim 6, wherein the sampling comprises sampling at substantially regular depths along the first and second well paths or sampling at intersections between the first and second well paths and the faces. a tetrahedron grid of the numerical model. The method of claim 6, wherein the sampling further comprises sampling at least one sample near an intersection between the first or second well path and a compatible discontinuity, fault, or horizon. defined in the numerical model. The method of claim 5, further comprising, after generating the second proposed well vertex based on the determined value of the implicit stratigraphic function, automatically adjusting a location of the second wellhead proposed on the base. first and second petrophysical logs respectively associated with the first and second boreholes, and wherein the automatic adjustment of the location of the second proposed wellhead comprises the iterative disturbance of an offset or a stretching / compressing factor and correlating the first and second petrophysical logs in a neighborhood of the proposed first and second well vertices. The method according to any one of the preceding claims, wherein said at least one structural element comprises a geological map of an intermediate geological horizon, and wherein the intermediate geological horizon is not used to constrain the numerical model before that it be generated. The method of any of the preceding claims, wherein: the subterranean formation data comprises a seismic image; the location in the volume concerned corresponds to a point in the seismic image; access to the numerical model for determining the value of the implicit stratigraphic function includes determining the value of the implicit stratigraphic function at the point in the seismic image; and generating at least one structural element comprises generating a surface or a plurality of points in the seismic image on the basis of the determined value of the implicit stratigraphic function. The method of any of the preceding claims, wherein: determining the location in the volume of interest comprises determining a plurality of locations in the relevant volume; Access to the digital model for determining the value of the implicit stratigraphic function includes: determining the value of the implicit stratigraphic function for each of the given plurality of locations; and determining a remainder for each of the determined plurality of locations from the determined value for each of the plurality of locations; and generating at least one structural element comprises generating a surface or a plurality of points based on the determined value and the determined remainder for each of the plurality of locations. The method of claim 12, wherein the remainder is interpolated, wherein determining the remainder for each of the plurality of locations includes determining the remainder at a first location among the plurality of locations as a difference between the value. the implicit stratigraphic function for the first location and an arbitrarily selected value, and wherein the method further comprises updating the implicit stratigraphic function by summing the determined remainder for each of the plurality of locations with the determined value for the implicit stratigraphic function for each of the plurality of locations. Apparatus, comprising: at least one hardware-based processing unit in a computer; and a program code configured upon execution by said at least one processing unit to generate structural information for a subterranean formation containing extractable hydrocarbons using the method of any one of claims 1 to 13. A computer program product, comprising: program code instructions stored on the computer readable medium and configured to, when said program is executed by a computer, perform the steps of the method according to any one of claims 1 to 13 to generate structural information for an underground formation containing extractable hydrocarbons.